212 research outputs found
Skeletal Torsion Tunneling and Methyl Internal Rotation: The Coupled Large Amplitude Motions in Phenyl Acetate
The rotational spectrum of phenyl acetate, CH3 COOC6 H5, is measured using a free jet absorption millimeter-wave spectrometer in the range from 60 to 78 GHz and two pulsed jet Fourier transform microwave spectrometers covering a total frequency range from 2 to 26.5 GHz. The features of two large amplitude motions, the methyl group internal rotation and the skeletal torsion of the CH3 COO group with respect to the phenyl ring C6 H5 (tilted at about 70◦ ), characterize the spectrum. The vibrational ground state is split into four widely spaced sublevels, labeled as A0, E0, A1, and E1, each of them with its set of rotational transitions and with additional interstate transitions. A global fit of the line frequencies of the four sublevels leads to the determination of 51 spectroscopic parameters, including the ∆EA0/A1 and ∆EE0/E1 vibrational splittings of ~36.4 and ~33.5 GHz, respectively. The V3 barrier to methyl internal rotation (~136 cm−1 ) and the skeletal torsion B2 barrier to the orthogonality of the two planes (~68 cm−1 ) are deduced
Gender gaps in urban mobility
Abstract Mobile phone data have been extensively used to study urban mobility. However, studies based on gender-disaggregated large-scale data are still lacking, limiting our understanding of gendered aspects of urban mobility and our ability to design policies for gender equality. Here we study urban mobility from a gendered perspective, combining commercial and open datasets for the city of Santiago, Chile. We analyze call detail records for a large cohort of anonymized mobile phone users and reveal a gender gap in mobility: women visit fewer unique locations than men, and distribute their time less equally among such locations. Mapping this mobility gap over administrative divisions, we observe that a wider gap is associated with lower income and lack of public and private transportation options. Our results uncover a complex interplay between gendered mobility patterns, socio-economic factors and urban affordances, calling for further research and providing insights for policymakers and urban planners
The Glial Regenerative Response to Central Nervous System Injury Is Enabled by Pros-Notch and Pros-NFκB Feedback
Organisms are structurally robust, as cells accommodate changes preserving structural integrity and function. The molecular mechanisms underlying structural robustness and plasticity are poorly understood, but can be investigated by probing how cells respond to injury. Injury to the CNS induces proliferation of enwrapping glia, leading to axonal re-enwrapment and partial functional recovery. This glial regenerative response is found across species, and may reflect a common underlying genetic mechanism. Here, we show that injury to the Drosophila larval CNS induces glial proliferation, and we uncover a gene network controlling this response. It consists of the mutual maintenance between the cell cycle inhibitor Prospero (Pros) and the cell cycle activators Notch and NFκB. Together they maintain glia in the brink of dividing, they enable glial proliferation following injury, and subsequently they exert negative feedback on cell division restoring cell cycle arrest. Pros also promotes glial differentiation, resolving vacuolization, enabling debris clearance and axonal enwrapment. Disruption of this gene network prevents repair and induces tumourigenesis. Using wound area measurements across genotypes and time-lapse recordings we show that when glial proliferation and glial differentiation are abolished, both the size of the glial wound and neuropile vacuolization increase. When glial proliferation and differentiation are enabled, glial wound size decreases and injury-induced apoptosis and vacuolization are prevented. The uncovered gene network promotes regeneration of the glial lesion and neuropile repair. In the unharmed animal, it is most likely a homeostatic mechanism for structural robustness. This gene network may be of relevance to mammalian glia to promote repair upon CNS injury or disease
Effect of C-2 substitution on the stability of non-traditional cephalosporins in mouse plasma
This work is licensed under a Creative Commons Attribution 4.0 International License.A systematic study of the stability of a set of cephalosporins in mouse plasma reveals that cephalosporins lacking an acidic moiety at C-2 may be vulnerable to β-lactam cleavage in mouse plasma
Testing the Homogeneity of Type Ia Supernovae in the Near-Infrared for Accurate Distance Estimations
Type Ia Supernovae (SNe Ia) have been extensively used as standardisable
candles in the optical for several decades. However, SNe Ia have shown to be
more homogeneous in the near-infrared (NIR), where the effect of dust
extinction is also attenuated. In this work, we explore the possibility of
using a low number of NIR observations for accurate distance estimations, given
the homogeneity at these wavelengths. We found that one epoch in and/or
band, plus good -band coverage, gives an accurate estimation of peak
magnitudes in () and () bands. The use of a single
NIR epoch only introduces an additional scatter of mag for epochs
around the time of -band peak magnitude (). We also tested the
effect of optical cadence and signal-to-noise ratio (S/N) in the estimation of
and its uncertainty propagation to the NIR peak magnitudes. Both
cadence and S/N have a similar contribution, where we constrained the
introduced scatter of each to mag in and in
. However, these effects are expected to be negligible, provided the
data quality is comparable to that obtained for observations of nearby SNe
(). The effect of S/N in the NIR was tested as well. For SNe Ia
at , NIR observations with better S/N than that found in the
CSP sample is necessary to constrain the introduced scatter to a minimum
( mag). These results provide confidence for our FLOWS project
that aims in using SNe Ia with public ZTF optical light curves and few NIR
epochs to map out the peculiar velocity field of the local Universe. This will
allow us to determine the distribution of dark matter in our own supercluster,
Laniakea, and test the standard cosmological model by measuring the growth rate
of structures, parameterised by , and the Hubble-Lema\^itre constant,
.Comment: Accepted in A&
The Atonal Proneural Transcription Factor Links Differentiation and Tumor Formation in Drosophila
The acquisition of terminal cell fate and onset of differentiation are instructed by cell type–specific master control genes. Loss of differentiation is frequently observed during cancer progression, but the underlying causes and mechanisms remain poorly understood. We tested the hypothesis that master regulators of differentiation may be key regulators of tumor formation. Using loss- and gain-of-function analyses in Drosophila, we describe a critical anti-oncogenic function for the atonal transcription factor in the fly retina, where atonal instructs tissue differentiation. In the tumor context, atonal acts by regulating cell proliferation and death via the JNK stress response pathway. Combined with evidence that atonal's mammalian homolog, ATOH1, is a tumor suppressor gene, our data support a critical, evolutionarily conserved, function for ato in oncogenesis
Routes of importation and spatial dynamics of SARS-CoV-2 variants during localized interventions in Chile
Human mobility is strongly associated with the spread of SARS-CoV-2 via air travel on an international scale and with population mixing and the number of people moving between locations on a local scale. However, these conclusions are drawn mostly from observations in the context of the global north where international and domestic connectivity is heavily influenced by the air travel network; scenarios where land-based mobility can also dominate viral spread remain understudied. Furthermore, research on the effects of nonpharmaceutical interventions (NPIs) has mostly focused on national- or regional-scale implementations, leaving gaps in our understanding of the potential benefits of implementing NPIs at higher granularity. Here, we use Chile as a model to explore the role of human mobility on disease spread within the global south; the country implemented a systematic genomic surveillance program and NPIs at a very high spatial granularity. We combine viral genomic data, anonymized human mobility data from mobile phones and official records of international travelers entering the country to characterize the routes of importation of different variants, the relative contributions of airport and land border importations, and the real-time impact of the country's mobility network on the diffusion of SARS-CoV-2. The introduction of variants which are dominant in neighboring countries (and not detected through airport genomic surveillance) is predicted by land border crossings and not by air travelers, and the strength of connectivity between comunas (Chile's lowest administrative divisions) predicts the time of arrival of imported lineages to new locations. A higher stringency of local NPIs was also associated with fewer domestic viral importations. Our analysis sheds light on the drivers of emerging respiratory infectious disease spread outside of air travel and on the consequences of disrupting regular movement patterns at lower spatial scales
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